1. IV FLOW RATES

2. INTRODUCTION
The pharmacy staff is responsible for calculating the flow rate of a medication to be administered intravenously.
This rate is expressed in terms of how many milliliters per hour or drops per minute a patient should receive.
It can also be expressed in terms of how much IV fluid should be prepared per shift or per day.
Often referred to as the infusion rate or rate of infusion.

3. Volume of fluid or amount of drug to be infused
DURATION OF THERAPY
The duration of therapy may be calculated using the following formula:
Duration of therapy =
Volume of fluid or amount of drug to be infused
Flow rate
*Flow rate = ml/hr
*When calculating the duration of therapy, always round your answer down to the whole hour.

4. EXAMPLE PROBLEM DURATION OF THERAPY
A 1 L IV is running at 125 mL/hour. How often will you send up a new bag?
X hours = mL
125 mL/hour
= 8 hours

5. ANOTHER EXAMPLE PROBLEM DURATION OF THERAPY
If an IV is running at 150 mL/hour and three 1 L bags are sent to the floor, how long will these bags last? X hours = the time the 3 bags will last X hours = 3000 mL 150 mL/hour = 20 hours

6. Volume of fluid or amount of drug to be infused
FLOW RATE
When an order specifies a volume or amount of drug to be given over a specific period of time, the flow rate (mL/hr) can be calculated using the following formula:
Flow rate =
Volume of fluid or amount of drug to be infused
Duration of therapy

7. EXAMPLE PROBLEM #1 FLOW RATE
The following order is sent to the IV room: Medication: Solu-Cortef 300 mg Fluid volume: 300 mL Time of infusion: 4 hours What volume of fluid is given per hour, and what amount of drug is given per hour?

8. TO SOLVE PROBLEM…….
FIRST: Determine the volume of fluid given per hour. 300 mL / 4 hours = 75 mL/hour SECOND: Calculate the amount of drug given per hour. 300 mg / 4 hours = 75 mg/hour

9. EXAMPLE PROBLEM #2 FLOW RATE
The following order is sent to the IV room. Medication: Cefazolin 500 mg Fluid volume: 50 mL Time of infusion: ½ hour What volume of fluid is given per hour, and what amount of drug is given per hour?

10. TO SOLVE PROBLEM…….
FIRST: Determine the volume of fluid given per hour. 50 mL / 0.5 hours = 100 mL/hour SECOND: Calculate the amount of drug given per hour. 500 mg / 0.5 hours = 1000 mg/hour

11. EXAMPLE PROBLEM #3 FLOW RATE
A 500ml IV bag is administered over 4 hours. What is the flow rate? TO SOLVE: mL/hr = 500mL/4hr X = 500/4 = 125 X = 125mL/hr

12. EXAMPLE PROBLEM #4 FLOW RATE
Run KCL 10MEQ in D5W 1000 ml at 80 mL/hour. How many mL/min would this run? FIRST: determine what is pertinent information to solve the problem TO SOLVE: mL/1 min = 80 mL/60 min X = 80/60 X = 1.33 mL/min

13. DROP SETS
Pharmacy staff and the nursing staff are responsible for calculating the rate of administration for IV fluids in a drops per minute rate (expressed gtt/min).
The abbreviation gtt comes from the Latin word guttae, which means “drops.”
An IV set is identified by the number of drops it takes to make 1 mL. This calibration is referred to as a drop set or drip set.

14. DROP SETS
IV sets are designed to administer medication at different rates.
The most common sets are:
10, or 10 gtt/mL
15, or 15 gtt/mL
20, or 20 gtt/mL
60, or 60 gtt/mL (AKA mini drip set)

15. DROP SETS
The drop sizes for the 10,15, and 20 calibrations produce macrodrops.
The 60 calibration produces microdrops.
The 60 gtt/mL is called a mini-drip set.

16. Pharmacy Calculations, Fourth Edition
INFUSION RATES
The infusion rate, measured in drops per minute, is calculated as follows :
x gtt/min = Flow Rate x Drop size
60min/1hr
Flow Rate = ml/hr
Drop size = gtt/ml
(Round down to a whole drop when a drop per minute calculation results in a partial drop)
Equation appears on page 189
© Paradigm Publishing, Inc.

17. EXAMPLE PROBLEM #1 INFUSION RATE
Pharmacy Calculations, Fourth Edition
EXAMPLE PROBLEM #1 INFUSION RATE
If an IV is running at 60 mL/hr, what is the rate in drops per minute using a 15 drop set?
x gtt/min = (60 mL/1 hour) x (15 gtt/mL)
60 min/hour
= 15 gtt/min
Example 7.3.1, pages 189 and 190
© Paradigm Publishing, Inc.

18. EXAMPLE PROBLEM #2 INFUSION RATE
You have D5W infusing at 80ml/hr. What is the infusion rate in gtt/min if there are 30gtts/ml? x gtt/min = (80 mL/1 hour) x (30 gtt/mL) = 40 gtt/min 60 min/hour